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view src/build-msvctools/math/fpclassify.c @ 3061:f8299bb6c872

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Initial support for native MSVC compilation. * add MSVC support files: compiler wrappers and support libraries * adapt libiconv to work with MSVC * adapt gettext to work with MSVC
author Michael Goffioul <michael.goffioul@gmail.com>
date Mon, 17 Jun 2013 22:43:11 -0400
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#include <math.h>

/* 'fxam' sets FPU flags C3,C2,C0   'fstsw' stores: 
 FP_NAN			001		0x0100
 FP_NORMAL		010		0x0400
 FP_INFINITE		011		0x0500
 FP_ZERO		100		0x4000
 FP_SUBNORMAL		110		0x4400

and sets C1 flag (signbit) if neg */

int __fpclassify (double _x){
  unsigned short sw;
  __asm__ (
	"fxam; fstsw %%ax;"
	: "=a" (sw)
	: "t" (_x)
	);
  return sw & (FP_NAN | FP_NORMAL | FP_ZERO );
}